PHP实现过滤各种HTML标签

$str=preg_replace("/<s*imgs+[^>]*?srcs*=s*('|")(.*?)1[^>]*?/?s*>/i","",$str); //过滤img标签
$str=preg_replace("/s+/",$str); //过滤多余回车
$str=preg_replace("/<[ ]+/si","<",$str); //过滤<__("<"号后面带空格)
$str=preg_replace("/<!--.*?-->/si",$str); //注释
$str=preg_replace("/<(!.*?)>/si",$str); //过滤DOCTYPE
$str=preg_replace("/<(/?html.*?)>/si",$str); //过滤html标签
$str=preg_replace("/<(/?head.*?)>/si",$str); //过滤head标签
$str=preg_replace("/<(/?meta.*?)>/si",$str); //过滤meta标签
$str=preg_replace("/<(/?body.*?)>/si",$str); //过滤body标签
$str=preg_replace("/<(/?link.*?)>/si",$str); //过滤link标签
$str=preg_replace("/<(/?form.*?)>/si",$str); //过滤form标签
$str=preg_replace("/cookie/si","COOKIE",$str); //过滤COOKIE标签
$str=preg_replace("/<(applet.*?)>(.*?)<(/applet.*?)>/si",$str); //过滤applet标签
$str=preg_replace("/<(/?applet.*?)>/si",$str); //过滤applet标签
$str=preg_replace("/<(style.*?)>(.*?)<(/style.*?)>/si",$str); //过滤style标签
$str=preg_replace("/<(/?style.*?)>/si",$str); //过滤style标签
$str=preg_replace("/<(title.*?)>(.*?)<(/title.*?)>/si",$str); //过滤title标签
$str=preg_replace("/<(/?title.*?)>/si",$str); //过滤title标签
$str=preg_replace("/<(object.*?)>(.*?)<(/object.*?)>/si",$str); //过滤object标签
$str=preg_replace("/<(/?objec.*?)>/si",$str); //过滤object标签
$str=preg_replace("/<(noframes.*?)>(.*?)<(/noframes.*?)>/si",$str); //过滤noframes标签
$str=preg_replace("/<(/?noframes.*?)>/si",$str); //过滤noframes标签
$str=preg_replace("/<(i?frame.*?)>(.*?)<(/i?frame.*?)>/si",$str); //过滤frame标签
$str=preg_replace("/<(/?i?frame.*?)>/si",$str); //过滤frame标签
$str=preg_replace("/<(script.*?)>(.*?)<(/script.*?)>/si",$str); //过滤script标签
$str=preg_replace("/<(/?script.*?)>/si",$str); //过滤script标签
$str=preg_replace("/javascript/si","Javascript",$str); //过滤script标签
$str=preg_replace("/vbscript/si","Vbscript",$str); //过滤script标签
$str=preg_replace("/on([a-z]+)s*=/si","On1=",$str); //过滤script标签
$str=preg_replace("//si","&＃",$str); //过滤script标签

function delhtml($str){  //清除html标签
$st=-1; //开始
$et=-1; //结束
$stmp=array();
$stmp[]="?";
$len=strlen($str);
for($i=0;$i<$len;$i++){
  $ss=substr($str,$i,1);
  if(ord($ss)==60){ //ord("<")==60
  $st=$i;
  }
  if(ord($ss)==62){ //ord(">")==62
  $et=$i;
  if($st!=-1){
   $stmp[]=substr($str,$st,$et-$st+1);
  }
  }
}
$str=str_replace($stmp,$str);
return $str;
}

function clear_html_label($html) 
{ 
$search = array ("'<script[^>]*?>.*?</script>'si","'<[/!]*?[^<>]*?>'si","'([rn])[s]+'","'&(quot|#34);'i","'&(amp|#38);'i","'&(lt|#60);'i","'&(gt|#62);'i","'&(nbsp|#160);'i","'&(iexcl|#161);'i","'&(cent|#162);'i","'&(pound|#163);'i","'&(copy|#169);'i","'(d+);'e"); 
$replace = array ("","1",""","&",">"," ",chr(161),chr(162),chr(163),chr(169),"chr(1)");
return preg_replace($search,$replace,$html); 
}